A Systematic Literature Review about Team Diversity and Team Performance: Future Lines of Investigation

This study aims to identify the different research paths that help us understand the emerging aspects explaining how team diversity influences team performance. We also present future lines of investigation that could help us to understand this theme. The study is a systematic literature review (SLR) of articles collected from the Web of Science (WoS) database, within management or business categories, published between 1996 and 2020, considering knowledge diversity, team heterogeneity, team wisdom, cross-functional project teams, and team composition. This study enables the systematization of the existing literature. The framework presented is based on the reviewed articles and explains the articulation of the concepts of team diversity and team performance based on three literature clusters, namely: (1) Team Knowledge Diversity, (2) Diversity Effects and (3) Desirable Outcomes of Diversity. Therefore, this work enriches the systematization of the academic literature on this topic, providing an original framework and a future research agenda organized by


Introduction
Diversity in the workplace has received significant interest in organizations looking to attract and retain talented employees, create broader knowledge bases, and increase the multidisciplinary nature of research and development (R&D) teams to benefit innovation processes. Diversity in the workplace also allows scientific developments that bridge gaps and reduce the time-to-market (Martinez et al. 2017). However, prior research on team diversity revealed mixed results, with the effects of team diversity ranging between positive, neutral, and negative (Jackson and Joshi 2004). Thus, a systematic literature review (SLR) (Tshetshema and Chan 2020) that explores how demographic diversity affects innovation performance in terms of creativity and innovation at the team level is necessary.
Globalization is already here (Kim and McLean 2015), and the trend towards the globalization of markets will become increasingly important in the 21st century (Tan and Sousa 2013). The emerging global economy is characterized by knowledge-intensive firms requiring diverse, specialized knowledge workers with particular knowledge competencies collaborating to create new knowledge that enhances organizational performance (Tenkasi and Boland 1996). Teams are essential building blocks of contemporary organizations. In this context, the factors contributing to team performance are the subject of multiple studies that contribute to the comprehension of achieving team effectiveness and high performance in a constantly changing environment (Dreu 2002).
Studies have focused on different team typologies based on theoretical perspectives, such as the upper-echelons theory, similarity-attraction theory, and social categorization, or social-identity theory. Team types usually include project teams, virtual teams, top management teams, R&D teams, new product development teams, student/academic (Tranfield et al. 2003). Since the purpose of this study is to identify literature clusters and present a future research agenda, we chose to apply the methodology described by Tranfield et al. (2003). Figure 1 shows the research protocol, giving the set of criteria that was built upon to answer the research questions.
Relevant articles for the topic analyzed were gathered from Web of Science (WoS) database. The WoS is a selective citation index of scientific and scholarly publishing; it is the world's oldest, most widely used and authoritative database of research (Birkle et al. 2020). A long and well established network provides a wide number of peer-reviewed publications and their respective bibliographic information ). Furthermore, due to its content, structure and detail, the WoS database is often selected as the only source for gathering data to develop systematic literature reviews (e.g., Fernandes and Ferreira 2021;Marchiori andFranco 2020 or Figueiredo and. We used the following keywords: "Knowledge Diversity", "Team Heterogeneity", "Team Wisdom", "Team Diversity", "Cross-functional Project Team", "Team Composition", "Start-up" and "Spin-off". The research was refined by choosing articles by document type, in English, within the Business Economics research area, and in the Management or Business Web of Science categories. The search was carried out on 31 March 2020, resulting in 80 articles.
The 80 articles obtained from WoS were submitted to VOSviewer software. We first "create a map based on bibliographic data" and then "read data from bibliographic database files" based on an information file originating in the WoS database. Next, we selected "bibliographic coupling" as the type of analysis, "documents" as the unit of analysis, and "full-counting" as the method. In the next step, we included documents with five as the "minimum number of citations of a document".
Application of the software allowed automatic identification of three clusters, including only 51 articles, "the largest set of connected items". Cluster 1 had 24 items, Cluster 2 was formed of 17 items, and Cluster 3 featured 10 items. The research used version 1.6.13 of VOSviewer software to present bibliometric maps and identify bibliographic coupling of document references. Kessler (1963) introduced the bibliographic coupling method, according to which two documents are considered bibliographically coupled when they use the same item as a cited reference. This approach identifies the relations between authors according to cited references, allowing identification of the most proactive research and giving a dynamic perspective of the area covered (Zhao and Strotmann 2008).
Next, the papers were read to identify the most significant teams emerging in each cluster formed in VOSviewer. This also resulted in a table in which we identified the objective of each article present in each cluster and determined the name given to each cluster.
Finally, according to Paul and Criado (2020), we can classify our study as a Bibliometric Review. Bibliometric reviews are characterized by analyzing an extensive amount of research using statistical tools to reveal trends. A bibliometric review can be developed using Viewer software programs, such as VoS (Visualization of Similarities), which is widely used to carry out this type of bibliometric review. Many bibliometric analyses are valuable when, given the number of existing articles, relatively few represent a major part of the total citations in the analysis (Paul and Criado 2020).
The present study followed the search protocol presented in Figure 1. Adm. Sci. 2022, 12, x FOR PEER REVIEW 4 of 25 The research protocol is complemented by Table 1, which presents the inclusion and exclusion criteria.

Inclusion Criteria Exclusion Criteria
Published in the period up until 31 March 2020~~~ Presence on Web of Science database~~~ Included in Business Economics areas~~~ Peer-reviewed scientific articles published in English~~~ Referring explicitly to "Knowledge Diversity", "Team Heterogeneity", "Team Wisdom", "Team Diversity", "Crossfunctional Project Team", "Team Composition", "Start-up" and "Spin-off" in the title, abstract or keywords In the search of the Web of Science database, proceedings papers, editorial material, book reviews, early access, meeting abstracts, reviews, letters and notes, notes, and erratum were excluded. ~~~ Bibliographic oupling with full counting of document analysis was performed using VOSviewer software, with a minimum number of five citations of a document. Figure 2 shows the evolution in the number of publications and citations per year, considering the 80 articles from 1996 to 2020. The first article was published in 1996, and since then, the number of articles has increased, reaching a maximum of 12 in 2019. Citations reached a maximum of 607 in 2019. Based on the evolution of the number of citations and publications, increasing interest has been demonstrated, particularly since 2010, when the relationship between diversity and performance began to receive more attention.

Results
Of the 80 articles researched, 43 (53.75%) have more than 10 citations, and only 8 (10%) do not have any. The research protocol is complemented by Table 1, which presents the inclusion and exclusion criteria. Table 1. Criteria for inclusion and exclusion of publications in the SLR.

Inclusion Criteria Exclusion Criteria
Published in the period up until 31 March 2020 Presence on Web of Science database Included in Business Economics areas Peer-reviewed scientific articles published in English Referring explicitly to "Knowledge Diversity", "Team Heterogeneity", "Team Wisdom", "Team Diversity", "Cross-functional Project Team", "Team Composition", " Start-up" and "Spin-off" in the title, abstract or keywords In the search of the Web of Science database, proceedings papers, editorial material, book reviews, early access, meeting abstracts, reviews, letters and notes, notes, and erratum were excluded. Bibliographic oupling with full counting of document analysis was performed using VOSviewer software, with a minimum number of five citations of a document. Figure 2 shows the evolution in the number of publications and citations per year, considering the 80 articles from 1996 to 2020. The first article was published in 1996, and since then, the number of articles has increased, reaching a maximum of 12 in 2019. Citations reached a maximum of 607 in 2019. Based on the evolution of the number of citations and publications, increasing interest has been demonstrated, particularly since 2010, when the relationship between diversity and performance began to receive more attention.

Results
Of the 80 articles researched, 43 (53.75%) have more than 10 citations, and only 8 (10%) do not have any. Table 2 presents the top ten most-cited articles included in this study, which make up a total of 2884 citations. Despite not being a new research trend, the debate on team diversity's impact on firm performance reveals a strong tendency to focus only on TMT diversity. Recognizing the paramount importance of the impact of diversity on performance, since 2012, research has started to explore diversity in its related subfields and to consider diversity outside of TMT.   Table 2 presents the top ten most-cited articles included in this study, which make up a total of 2884 citations. Despite not being a new research trend, the debate on team diversity's impact on firm performance reveals a strong tendency to focus only on TMT diversity. Recognizing the paramount importance of the impact of diversity on performance, since 2012, research has started to explore diversity in its related subfields and to consider diversity outside of TMT.   To identify the tendencies in previous research on team diversity and team performance, a bibliographic coupling of document references with a minimum of five citations was carried out, resulting in the definition of three clusters, involving fifty-one articles. Table 3 presents the clusters.  The clusters were analyzed and named: (1) Team Knowledge Diversity, (2) Diversity Effects and (3) Desirable Outcomes of Diversity. Figure 3 shows the cluster network. Cluster 1 is composed of 24 items addressing Team Knowledge Diversity and how this is influenced by organizational context and employees' individual characteristics. Table 4 lists the articles of Cluster 1 and presents the studies' objectives, methodology, and citations. Cluster 1 includes 18 (75%) articles based on a quantitative approach, 5 Cluster 1 is composed of 24 items addressing Team Knowledge Diversity and how this is influenced by organizational context and employees' individual characteristics. Table 4 lists the articles of Cluster 1 and presents the studies' objectives, methodology, and citations. Cluster 1 includes 18 (75%) articles based on a quantitative approach, 5 Cluster 1 is composed of 24 items addressing Team Knowledge Diversity and how this is influenced by organizational context and employees' individual characteristics. Table 4 lists the articles of Cluster 1 and presents the studies' objectives, methodology, and citations. Cluster 1 includes 18 (75%) articles based on a quantitative approach, 5 (21%) based on a qualitative approach, and 1 (4%) on mixed methodology. Cluster 1 is composed of 24 items addressing Team Knowledge Diversity and how this is influenced by organizational context and employees' individual characteristics. Table 4 lists the articles of Cluster 1 and presents the studies' objectives, methodology, and citations. Cluster 1 includes 18 (75%) articles based on a quantitative approach, 5 (21%) based on a qualitative approach, and 1 (4%) on mixed methodology.
In Cluster 1, several main themes were identified. First, there is the need to approach team diversity based on the evolution of organizational work structures (van Knippenberg and Mell 2016). Secondly, there are challenges that emerge from team diversity (Hoisl et al. 2017;Martinez et al. 2017;van Knippenberg and Mell 2016) and how it is possible to explore diversity in order to pursue synergistic benefits (Kavadias and Sommer 2009;Kristinsson et al. 2016;van Knippenberg and Mell 2016). It is also important to analyze the importance of cognitive team diversity in team creativity (Men et al. 2019;Shin et al. 2012;Tang and Naumann 2016) and its effects on team performance (Lin 2011;Trischler et al. 2017). Diversity should also be approached based on diversity integration (Tenkasi and Boland 1996) and diversity coordination (Zoogah et al. 2011).
Over the last five decades, changes have been identified in the workforce, in employee mobility, and in greater levels of specialization, allied to the increasing tendency to organize work in team-based structures, creating increasing numbers of heterogeneous organizations (van Knippenberg and Mell 2016).
The focus of the global economy has changed from capital-and labor-intensive firms to knowledge-intensive firms; there is now a significant demand for high knowledge competence, in which collaboration is crucial to improve organizational performance. Simultaneously, the development of information technologies is an integral part of knowledgeintensive firms. This allows mutual learning but fails to consider the necessary dialog among highly differentiated fields of expertise as a basis for integration (Tenkasi and Boland 1996). Existing research focuses on the moderators of team diversity's effects, but it is also important to make a more integrative effort (van Knippenberg and Mell 2016).
The concept of hybrid organizations is based on the heterogeneity (e.g., education, family, professional experience) of entrepreneurial teams and its enhancement of entrepreneurial processes (Dufays and Huybrechts 2016). However, diversity could also present some challenges associated with team traits and team composition (Hoisl et al. 2017;Martinez et al. 2017;van Knippenberg and Mell 2016). For example, the exposure of innovation projects through internet broadcasting could affect individuals' extrinsic (e.g., desire for monetary rewards) and intrinsic (e.g., enjoyment) motivations and knowledge diversity with repercussions for the performance of open-innovation projects (Frey et al. 2011). This is because innovation requires a broad knowledge base, and organizations count on team diversity to create a multidisciplinary solution to identify scientific developments and gain greater cognitive ability. However, diversity will present distinct effects, depending on the novelty of innovation and industry (Martinez et al. 2017). We should also acknowledge that diversity and excessive heterogeneity could also harm R&D team performance and, acknowledging this diversity, organizations should consider the ideal mix of capacities to maximize the benefit of creativity in diverse R&D teams, avoiding the conflict and distrust normally associated with diversity (Martinez et al. 2017). Another negative aspect related to R&D team diversity is hyper-competition, arising from the constant challenge to improve competitiveness, an aspect that can differ according to the organization's size or age (Hoisl et al. 2017).
Diversity should be explored in order to pursue synergistic benefits through access to a wider range of resources that allow better decision-making, problem-solving, flexibility, creativity, and innovation (van Knippenberg and Mell 2016), generating group solutions (Kavadias and Sommer 2009), and creating better entrepreneurial decision-making processes (Kristinsson et al. 2016). It is possible to observe social structural conditions in which the role of innovation catalysts emerges: individuals that support, facilitate and promote their colleagues' innovativeness (Tortoriello et al. 2015).
It is also possible to explore diversity benefits according to team typology. For instance, Choudhury and Haas (2018) analyzed the importance of patenting teams' composition and their outcomes (the scope of their patent applications and the speed of their patent approvals) based on team members' diversity and on team leader experience. Furthermore, in design-intensive industries, where customers are extremely watchful of product design, collaboration teams are a critical issue. Managing collaborations is also critical, forcing firms to develop a proper collaborative strategy focused not only on a collaborator's individual characteristics but also working to build a balanced portfolio of collaborators (Dell'Era and Verganti 2010). In co-design teams, team background diversity and motivation should be considered in selection to enable the team's collaborative efforts to transform relevant knowledge into innovative outcomes (Trischler et al. 2017).
In firms with greater knowledge diversity, it is possible to make more effective strategic alliances and acquisitions, and firms with low knowledge diversity make more effective R&D investments; therefore, a knowledge portfolio is crucial to measure the effectiveness of knowledge-sourcing and the success of inter-firm partnership strategies (Lin 2011). A further topic addressed in research is whether and when team diversity is positively related to individual creativity; the research is based on four personal characteristics, namely, openness to experience, creative self-efficacy, preference for divergence, and individual creativity (Shin et al. 2012). Individual differences and situational factors are essential to enable individual contributions to maximize team diversity and contribute to team creativity, an aspect that could be enhanced in the presence of high levels of transformational leadership (Shin et al. 2012). Tang and Naumann (2016) researched the team diversity-team creativity relationship and identified knowledge-sharing as a moderator in the positive impact of team diversity interaction as well as the effect of positive mood on team creativity outcomes.
According to social identity theory and through educational background, team diversity could have a positive influence on information use or a negative influence through nationality (Dahlin et al. 2005). Diversity is a potential driver of new ventures' business success, and new teams' international diversity and approach (a greater or lesser degree of causation logic) could impact the entrepreneurial decision process (Kristinsson et al. 2016). It is also possible to analyze the level of diversity (surface-level and deep-level) in teams' helping behavior, namely cohesion and cooperation, using them as mediators of the impact of demographic characteristics and trait diversity (Liang et al. 2015).
Considering the convergence of several crucial diversity features, it is important to understand strategic alliance team coordination as strengthening the positive relation between functional background diversity and team effectiveness (Zoogah et al. 2011). It is also important to rely on higher information technology capacities to provide greater knowledge, strength, and diversity, allowing better stability in firms' performance (Chen and Liang 2016). Lower levels of conflict are found to have a positive impact on project efficiency, and the early definition of project goals is positively associated with better-quality coordination (Anthony et al. 2014).
In Cluster 1, the challenges faced by researchers are still quite evident in terms of clearly defining which aspects of diversity teams should focus on in order to structure their decision-making process so that they can benefit from the synergies arising from the diversity in their teams. Through access to a much wider range of resources originated by diversity, teams can form more and better decisions.
In future research regarding Cluster 1 (Team Knowledge Diversity) and considering the existing research, it is important to compare the strength of relationships between team member creativity and cognitive diversity-both perceived and actual (Shin et al. 2012). By recognizing the existence and possible ramifications of the existing trade-offs in organizing patenting activity in order to maximize scope versus speed, are promising directions for further research will be opened (Choudhury and Haas 2018).
Cluster 2: Diversity Effects Cluster 2 is composed of 17 items referring to diversity's effects on team performance and team coordination, and the influence of diversity on the approach to complexity in internationalization processes and strategic decisions. Table 5 lists the articles in Cluster 2 and presents the studies' objectives, methodology, and citations. Cluster 2 includes 13 articles (76%) based on a quantitative approach and 4 (24%) based on a qualitative approach.
Cluster 2 focuses on diversity's effects on team performance (Carpenter 2002;Jackson and Joshi 2004;Kilduff et al. 2000;Priem et al. 1999;Zhou and Rosini 2015). Team diversity concepts consist of several fundamental, interrelated facets that can shape firm performance, where diversity is identified as a strategic facilitator of change (Naranjo-Gil et al. 2008), with implications for the innovation process (Auh and Menguc 2005), helping to establish strategic innovation (Barkema and Shvyrkov 2007) and influencing the use of corporate venture capital (Sahaym et al. 2016). Furthermore, team diversity is also associated with the challenges of consensus achievement (Knight et al. 1999), making diversity a valuable asset through which to obtain a competitive advantage (Jackson and Joshi 2004), with positive impacts on competitive actions and responses (Hambrick et al. 1996).
As described by Carpenter (2002), the effects of team diversity on performance will depend upon the team's strategic and social context. Based on three aspects of the social context, namely the combination of diversity dimensions, the team manager's demographic characteristics, and the work unit's demography, Jackson and Joshi (2004) conclude that the demographic and social context moderates the interaction between team diversity and team performance.
Research also examines how team diversity affects the external evaluation of a team's business ideas, arguing that, from an information perspective, the task-related diversity of member characteristics enhances team effectiveness, and non-task diversity harms team effectiveness, distracting team members from their tasks (Der Foo et al. 2005).
Considering the importance of a team's strategic and social context and given the complexity of human decision processes in ambiguous, high-stake situations involving team processes, attitudes, and judgments, we need to determine which variables should be measured to understand strategic choices (Priem et al. 1999). We also need to consider the existence of a cycle of "homosocial reproduction" potentiated by executive team power, which is interrupted in the presence of environmental pressure and increased complexity (Boone et al. 2004). In a complex scenario, there is a positive effect of team education, work experience, and tenure on performance, an effect that is highly sensitive to complexity but that could represent a stronger relationship in short-tenured teams (Carpenter 2002).
According to Pitcher and Smith (2001), personality and power play a critical role in diversity proxies (e.g., of age, team tenure, industry experience, and functional background diversity) for cognitive diversity, supporting the notion that some forms of diversity are more relevant for strategic outcomes, such as innovation and performance. Increased functional coordination also creates a positive impact of TMT diversity on innovation (Auh and Menguc 2005). This extends prior research assumptions that TMT diversity increases strategic innovation, enriching this argument with a new possible approach based on exploring new geographical areas, considering that diversity may lead to the formation of TMT sub-groups, jeopardizing the communication process and the propensity to advance to new locations (Barkema and Shvyrkov 2007). International alliances could also be influenced by the relationship between TMT international exposure diversity and firm internationalization (Lee and Park 2006).

Authors
Article Objective Methodology Citations Anthony et al. (2014) Crossing functions above the cross-functional project team: The value of lateral coordination among functional department heads.
Approach the impact of quality of coordination of cross-functional project teams with different levels of boundary conflict.
Quantitative Sample: 60 cross-functional project teams. 9 Chen and Liu (2012) Impact of network position and knowledge diversity on knowledge creation: The empirical setting of research communities.
Analyze the role of network position and knowledge diversity in the process of new knowledge creation.

284
Dell'Era and Verganti (2010) Collaborative strategies in design-intensive industries: Knowledge diversity and innovation.
Addresses how a company may develop a collaborative strategy by identifying an effective portfolio of designers.
Quantitative Sample: A total of 121 teams that filed patents.

67
Dufays and Huybrechts (2016) Where do hybrids come from? Entrepreneurial team heterogeneity as an avenue for the emergence of hybrid organizations.
Explore the emergence of hybrid organizations.
Qualitative Theoretical approach.  49 Kristinsson et al. (2016) The relationship between founder team diversity and innovation performance: The Moderating role of causation logic.
Explore diversity and logic in new ventures and analyze the impact on entrepreneurial decision-making.

Quantitative Sample: A total of 157 new technology-based ventures in a Northern
European country.

Liang et al. (2015)
Team diversity and team helping behavior: The mediating roles of team cooperation and team cohesion.
Approach team-helping behavior as a collective phenomenon and as a mediator of the effects of team members' demographic diversity.
Quantitative Sample: Data from 558 employees in 133 work teams in Taiwanese firms.

Lin (2011)
Knowledge diversity as a moderator: Inter-firm relationships, R&D investment and absorptive capacity.
Analyze how knowledge diversity impacts firm performance in R&D investment, strategic alliances, and acquisitions.
Quantitative Sample: A total of 2404 firm-year data from United States technology firms.  Tenkasi and Boland (1996) Exploring knowledge diversity in knowledge intensive firms: a new role for information systems.
Approach the role of information systems integration as a way to benefit firm knowledge diversity in knowledge-intensive firms.

Qualitative Theoretical approach. 46
Tortoriello et al. (2015) Being a catalyst of innovation: The role of knowledge diversity and network closure.
Approach the social structural conditions analyzing how individuals support, facilitate and promote their colleagues' innovativeness, working as catalysts of innovation.
Quantitative Sample: A total of 276 researchers involved in research and development division of a large multinational high-tech company.  (2016) Past, present, and potential future of team diversity research: From compositional diversity to emergent diversity.
Review of the existing research on team diversity to present the current state of the field, the past and the potential way forward to an integrative theory in diversity research.
Based on strategic alliance, team, and diversity research, the authors suggest that strategic alliance team coordination moderates the relationship between strategic alliance team diversity (nationality and gender characteristics) and effectiveness.
Quantitative Sample: A total of 109 team members, 44 team leaders and 34 alliance executives involved with 44 strategic alliance teams in 15 firms.  Barkema and Shvyrkov (2007) Does top management team diversity promote or hamper foreign expansion?
Approach the impact of TMT diversity on strategic innovation and the propensity to advance to new geographical areas.
Quantitative Sample: Data on 2159 expansions of 25 companies over a period of more than three decades.
162 Boone et al. (2004) The genesis of top management team diversity.
Literature review based on the statement that executive team power strengthens a cycle of "homosocial reproduction", in the form of social capital, which is interrupted only when teams face compelling needs for diversity Qualitative Theoretical approach. 83 Carpenter (2002) The implications of strategy and social context for the relationship between top management team heterogeneity and firm performance.
Analyze the link between top management team (TMT) heterogeneity (education, work experience and tenure) and firm performance.  Kilduff et al. (2000) Top management-team diversity and firm performance: Examining the role of cognitions.
Explore the relationship between demographic and cognitive team diversity and the reciprocal effects of diversity and firm performance.
Quantitative Sample: Data from 35 simulated firms involving a total of 159 managers.  Knight et al. (1999) Top management team diversity, group process, and strategic consensus.
Analyze concepts from upper echelons, group process, and social cognition theories to explore how demographic diversity and group processes influence strategic consensus in TMT.

Quantitative
Sample: Data from 76 high-technology firms from the United States and Ireland.
385 Lee and Park (2006) Top team diversity, internationalization and the mediating effect of international alliances.
Explore the mediating effect of international alliances in the relationship between TMT job-related diversity and firm internationalization. Considering the importance of communication and consensus, Knight et al. (1999) analyzed the implications of demographic diversity. If analyzed in isolation, this reveals negative effects on strategic consensus. However, when associated with interpersonal conflict and agreement-seeking, it has a greatly improved relationship with strategic consensus. The TMT lifecycle undergoes an evolution from preserving multiple interpretations at the beginning of the team's lifecycle towards a more heedful interrelation near its end, revealing that these changes in team performance affect and are affected by cognitive diversity (Kilduff et al. 2000).
Other aspects of diversity must be considered and, due to the rapid emergence of interorganizational teams and their importance in improving organizations' responsiveness, it was necessary to analyze structural variables (e.g., team informational diversity, team boundedness, and extra team links), which raised the importance of including structural considerations in inter-organizational team management (Drach-Zahavy 2011). Diverse TMTs are more prepared to deal with refocusing organizations strategically and keeping up operational performance, particularly when the relationship is moderated by job-related TMT heterogeneity (Naranjo-Gil et al. 2008). If we consider entrepreneurial teams, team composition is normally considered a crucial factor of start-ups' performance, particularly in highly competitive markets, and it is fundamental to observe demographic, personality, and informational diversity and its influence on entrepreneurial team performance (Zhou and Rosini 2015). Entrepreneurial team performance dynamics evolve through the different stages of the spin-out process (research commercialization and opportunity recognition; organization in gestation; proof of viability and maturity) with implications for team composition, where new team members bring in different kinds of experience without interfering in the alignment of the initial team members. In the early stages of spin-off formation, the composition of the founding team tends to undergo drastic changes and, while these changes might be expected to embody team diversity, surprisingly, they do not (Vanaelst et al. 2006).
The existing research field is vast and uses a multitude of concepts that need to be explained in order to be used clearly and objectively. Determining the impact of teams' diversity on their performance and, consequently, on organizational performance involves establishing a solid theoretical basis that allows decision-making processes to be founded when constituting a team. This helps to achieve the best results and knowledge to avoid any negative effects that may arise from the team's diversity.
In Cluster 2, Diversity Effects, considering the critical importance of both personality and power for cognitive diversity, it was necessary to assess their individual impact on the strategy to make it more useful for managers (Pitcher and Smith 2001). With the evidence of a partial mediation effect, we need to explore how TMT international exposure diversity can influence firm internationalization (Lee and Park 2006).
Cluster 3: Desirable Outcomes of Diversity Cluster 3 is composed of 10 items from among the desirable outcomes of diversity. Highlighted in this cluster are some key aspects, namely the accomplishment of organizational ambidexterity, as well as diversity as a decision process support and as a catalyst of innovation. Table 6 lists the articles in Cluster 3, presenting the studies' objectives, methodology and citations. Cluster 3 includes nine articles (90%) based on a quantitative approach and one (10%) based on a qualitative approach.
Research is normally centered on the relationship between TMT diversity and organizational performance and neglects the interaction of the nature of the team process with TMT diversity (Boone and Hendriks 2009). According to the authors, there is a need to focus on team mechanisms (e.g., collaborative behavior, accurate information exchange, and decentralization of decision-making) to clearly analyze them as moderators of the impact of TMT diversity (e.g., functional background and locus-of-control) on financial performance. Research also identifies other neglected aspects, such as the corporate governance's influence on strategic options and its innovation management outcomes (Talke et al. 2010). Considering that, based on upper echelons theory, strategic choices are made by TMT, giving corporate governance major importance in strategic choices and the results of innovation processes (Talke et al. 2010(Talke et al. , 2011, it is also important to analyze the antecedents of a firm's strategic orientation, especially the influence of TMT diversity and its characteristics (e.g., educational, functional, industrial and organizational background), as well as how this impacts on innovation outcomes and firm performance (Talke et al. 2011).  Furthermore, Wu et al. (2011) analyzed the effects of pay disparity and resource slack as moderators of TMT diversity, concluding that pay imparity has a negative effect on TMT diversity and that resource slack differs according to the level of team pay imparity.
TMT diversity is an ambiguous concept that allows the emergence of new mental models and cognitive frames, but also, on the other hand, the difficult exchange of information and integration of differential knowledge (Li 2013). In this integration process, we also need to approach the CEO advice-seeking process in order to obtain strategic directions for future decisions, as well as analyzing the existing patterns of advice-seeking and how they could be influenced by environmental dynamism, competitive firm performance or team heterogeneity (Heyden et al. 2013). Homberg and Bui (2013) found that empirical research on TMT diversity in the decision-making process is inconclusive. There are conflicting points of view in the existing research, in which TMT diversity is described as a source of explorative activities, such as strategic change, and as a way to hinder integration, exerting negative effects on strategic change (Wu et al. 2011). In a diversity scenario, it is necessary to create collaborative behavior and information exchange for the synergic use of the diverse functional backgrounds to enhance the quality and effectiveness of organizational decisions without affecting locus-of-control diversity (Boone and Hendriks 2009).
The belief that diversity is a condition for the achievement of organizational ambidexterity is not consensual (García-Granero et al. 2018). García-Granero et al. (2018) approach TMT diversity (e.g., functional and age diversity) as a way to achieve a wider range of exploration and exploitation possibilities, but this could lead to disagreements and potential conflicts originating between different types of diversity; ambidexterity could be moderated by CEOs' cognitive trust and shared responsibility. The dilemma is over how to find a mechanism to manage the dual impact of team diversity to achieve organizational ambidexterity (Li 2013(Li , 2014. Despite the existence of multiple challenges, Li (2014) claims that TMT diversity positively influences organizational ambidexterity, developing strategic planning processes but also representing difficulties through emerging conflicts. Organizational ambidexterity allows the construction of social capital through TMTs and benefits information-sharing and knowledge integration in senior teams (Li 2013). The debates, comprehensiveness (Li et al. 2016), connectedness, trust and shared vision (Li 2013) involved in strategic decisions could mediate TMT diversity and ambidexterity innovation to enable an effective focus on ambidextrous innovation strategy.
This cluster contains research focusing on TMT diversity and organizational performance, where the interaction of the nature of the team process with TMT diversity is neglected (Boone and Hendriks 2009). There is a lack of clarity regarding the team mechanisms that could effectively work as positive moderators of the impact of TMT diversity on team performance (Boone and Hendriks 2009), creating ambiguity in the TMT diversity concept (Li 2013).
In Cluster 3, Desirable Impacts of Diversity, further investigation could explore the influence of TMT diversity on innovation strategy in different contexts and at different levels of complexity, where information diversity and heterogeneity in knowledge bases might become more important (Talke et al. 2011). Further research should also approach the distinct dimensions of TMT that could contribute to achieving organizational ambidexterity (Li 2013).

Discussion of Results
The reviewed articles enabled the development of a hypothesized framework to determine the impact of team diversity on team performance (Figure 4). ambidexterity innovation to enable an effective focus on ambidextrous innovation strategy.
This cluster contains research focusing on TMT diversity and organizational performance, where the interaction of the nature of the team process with TMT diversity is neglected (Boone and Hendriks 2009). There is a lack of clarity regarding the team mechanisms that could effectively work as positive moderators of the impact of TMT diversity on team performance (Boone and Hendriks 2009), creating ambiguity in the TMT diversity concept (Li 2013).
In Cluster 3, Desirable Impacts of Diversity, further investigation could explore the influence of TMT diversity on innovation strategy in different contexts and at different levels of complexity, where information diversity and heterogeneity in knowledge bases might become more important (Talke et al. 2011). Further research should also approach the distinct dimensions of TMT that could contribute to achieving organizational ambidexterity (Li 2013).

Discussion of Results
The reviewed articles enabled the development of a hypothesized framework to determine the impact of team diversity on team performance (Figure 4). Organizations want to attract and retain talented employees, creating a broader knowledge base and increasing teams' multidisciplinary nature (Martinez et al. 2017), with specialized knowledge workers with unique knowledge competencies that enhance the organization's performance (Tenkasi and Boland 1996). This diversity is affected by Organizations want to attract and retain talented employees, creating a broader knowledge base and increasing teams' multidisciplinary nature (Martinez et al. 2017), with specialized knowledge workers with unique knowledge competencies that enhance the organization's performance (Tenkasi and Boland 1996). This diversity is affected by contextual aspects, such as firm size (Chen and Liang 2016) and team size (Hoisl et al. 2017), innovation intensity (Martinez et al. 2017), team expertise area (Chen and Liang 2016), team information use (Dahlin et al. 2005) and team conflict (Anthony et al. 2014). It can also be affected by employees' individual characteristics, such as gender, educational diversity, national diversity, proficiency in English, tenure, ethnicity (Dahlin et al. 2005), professional experience (Dufays and Huybrechts 2016) and personality diversity (van Knippenberg and Mell 2016).
Diversity affects several team aspects, such as performance (Jackson and Joshi 2004), team coordination (Auh and Menguc 2005), the approach to complexity (Boone et al. 2004;Priem et al. 1999), team performance in internationalization processes (Carpenter 2002;Lee and Park 2006), the achievement of strategic consensus (Knight et al. 1999) and the ways in which teams take part in decision processes (Priem et al. 1999).
The review of the articles identified several research gaps. Table 7 summarizes the aspects to consider in future research about knowledge diversity. Table 7. Summary of suggestions for future research.

Cluster and Area Suggestions for Future Research
(1) Team Knowledge Diversity Compare the strength of relationships between team member creativity and cognitive diversity, perceived and actual. Approach how formal and informal patent team member diversity affects patent approval speed and how it relates to team leaders' general and specific experience.
(2) Diversity Effects Explore the components (e.g., personality and power) of cognitive diversity and their individual impact on strategic outcomes, such a innovation and performance. Analyze how TMT international exposure diversity can influence firm internationalization.
(3) Desirable Outcomes of Diversity Explore the influence of TMT diversity on innovation strategy at different levels of complexity. Explore the distinct dimensions of TMT diversity and their influence on achieving organizational ambidexterity.

Conclusions and Implications
Diversity presents distinct effects, depending on the level of innovation and the industry (Martinez et al. 2017), while excessive diversity can also affect team performance negatively. Diversity should be understood as an ideal mix of capacities (Martinez et al. 2017). Other negative aspects of diversity are related to hyper-competition, originating in the constant challenge to improve competitiveness, an asset that could be moderated by organizations' size or age (Hoisl et al. 2017).
One of the major perspectives on diversity is based on upper echelons theory, since strategic choices are made by TMTs, emphasizing the role of corporate governance in strategic choices and innovation outcomes (Talke et al. 2010(Talke et al. , 2011. Results will always be influenced by TMT diversity and its characteristics (e.g., educational, functional, industrial, and organizational background), with repercussions for innovation outcomes and firm performance (Talke et al. 2011). Another perspective is based on Absorptive Capacity theory, which allows the analysis of knowledge diversity's influence on strategic alliances and acquisition processes (Lin 2011), and better knowledge-sharing influences on team creativity (Men et al. 2019).
We posed two research questions: (i) What are the different research clusters that help us to understand team diversity's influence on team performance? (ii) What are the future lines per cluster of investigation that could help us to better understand team diversity's influence on team performance? Aiming to answer the research questions, we carried out an SLR, following a rigorous research protocol. The results revealed three clusters: (1) Team Knowledge Diversity, (2) Diversity Effects and (3) Desirable Outcomes of Diversity.
The theoretical implications of this article are the development of a framework that systematizes the relation between the different streams of research, clarifying the relations between concepts by presenting a visual contribution to the concept's articulation. The elaboration of the framework aims to illustrate a reality that, despite being complex, can be read and understood more easily. In this way, the concepts underlying the identified clusters can be read in a systematic way, reinforcing the possibility of thinking about this issue critically. They also present a future research agenda per cluster that could contribute to the elaboration of new studies to create a better understanding of team diversity's influence on team performance. Our framework identifies research gaps and proposes an integrated model to direct future research. Considering that in the last five decades, research on team diversity's relation with team performance has shown inconsistent results (van Veelen and Ufkes 2019), it is important to address the proposed research lines for a better understanding of the role played by team diversity in team performance. The practical implications can be operationalized by organizational managers in order to achieve a harmony of individual diversities, creating synergies that could benefit teams and organizational performance. The strategy could be supported by the concepts identified and their inter-relations.
Despite the existence of multiple studies analyzing team diversity and its impact on team performance, this research revealed several aspects that limit the comprehension of previously identified diversity traits in order to promote a dialog that allows the integration of the existing research to achieve effective team diversity synergies, based on greater levels of communication and coordination. The current range of team diversity research works as a barrier that places potentially positive results on hold. Considering environmental pressure and increased complexity, and given the importance of Team Diversity in innovation processes and innovation strategy, it is necessary to address the ambiguity of the Team Diversity concept, creating a clear definition of the relevant diversity traits and their implications according to team typology. On this basis, it will be possible to establish a Team Diversity concept to support a desirable impact on innovation outcomes and firm performance, with clear benefits to the improvement of decision-making processes. Diversity should also be used as a knowledge integrator and to support competitiveness, particularly in more complex environments.
The major limitation of this study is related to the fact that the search for articles with the keywords Start-up and Spin-Off, when articulated with Knowledge Diversity, Team Heterogeneity, Team Wisdom, Team Diversity, Cross-functional Project Team, and Team Composition, did not return relevant articles for analysis.